Process for forming a fluffed fibrous pulp batt

ABSTRACT

A PROCESS FOR FORMING A FLUFFED FIBROUS PULP BATT FOR USED IN SANITARY PRODUCTS WHEREIN THE FLUFFED FIBROUS PLUP BATT HAS MARKEDLY IMPROVED STRENGTH AND INTEGRITY WITH ONGER. STRONGER AND MORE UNIFORM FIBERS FOR PRODUCING GREATER LOFT, MOISTURE ABSORPTION AND DTRENGTH IN THE BATT. THE PROESS INCLUDES INCLUDES THE CONTINUOUS STEPS OF TREATING OF THE WET PULP TO EFFECT KINKING AND INTERLOCKING OF THE FIBERS, FORMING THE FIBERS INTO A WET PRESSED PULP SHEET, DRYING, MECHANICALLY FIBERIZING THE SHEET AND AIR-LAYING THE DEBONDED KINKED FIBERS TO FORM A FLUFFED PULP BATT WITH IMPROVED STRENGTH AND INTERGRITY DUE TO THE KINKED AND INTERLOCKED FIBER FORMATION. PREFERABLY, THE PROCESS ALSO INCLUDES THE STEPS OF PRODUCING A DILUTE, AQUEOUS SLURRY OF THE KINKED AND INTERLOCKED FIBERS AND INCORPORATING IN THE SLURRY A CATIONIC DEBONDING AGENT, SO THAT MINIMUM BREAKAGE OF THE FIBERS WILL URSULT DURING THE MECHANICAL FIBERIZING STEP DUE TO THE DEBONDING AGENT, FECT OF THAT CATIONIC DEBONDING AGENT, AND A FLUFFED PULP BATT WILL BE PRODUCED WITH MINIMUM FIBER BREAKAGE THEREIN,

3,809,604 Patented May 7., 1974 United StatesPatent 3,809,604 PROCESS FOR FORMING A FLUFFED FIBROUS PULP BA'IT Phillip Waite Estes, Aiken, S.C., assignor to Riegel Textile Corporation, New York, N.Y. No Drawing. Filed Aug. 2, 1972, Ser. No. 277,280

Int. Cl. D21d 3/00 US. Cl. 162-100 v 2 Claims ABSTRACT on THE DISCLOSURE A process for forming a fiuflfed fibrous pulp batt for use in sanitary products wherein the flutfed fibrous pulp batt has markedly improved strength and integrity with longer, stronger and more uniform fibers for producing greater loft, moisture absorption and strength in the batt. The process includes includes the continuous steps of treating of the wet pulp to effect kinking and interlocking of the fibers, forming the fibers into a wet pressed pulp sheet, drying, mechanically fiberizing the sheet and air-laying the debonded kinked fibers to form a fluffed pulp batt with improved strength and integrity due to the kinked and interlocked fiber formation. Preferably, the process also includes the steps of producing a dilute, aqueous slurry of the kinked and interlocked fibers and incorporating in the slurry a cationic debonding agent, so that minimum breakage of the fibers will result during the mechanical fiberizing step due to the debonding effect of that cationic debonding agent, and a fiufied pulp batt will be produced with minimum fiber breakage therein.

This invention relates to a process for improving a flutfed fibrous pulp batt adapted for use in sanitary products or the like wherein the fluffed fibrous pulp batt has markedly improved strength and integrity with longer, stronger and more uniform fibers for producing greater loft, moisture absoption and stength in the batt.

In sanitay products, such as sanitary napkins, diapers, etc., flutfed fibrous pulp batts have been utilized as the core material for providing absorbency and other characteristics in the sanitary products. These fiufied fibrous pulp batts are normally produced by manufacturing a wet pressed pulp sheet formed by conventional pulp and paper making processes and then mechanically fiberizing the wet pressed pulp sheet into individual fibers and airlaying the individual fibers to form a fiutfed fibrous pulp batt which may be cut and placed into the center or core of the sanitary products.

In such flutted fibrous pulp batts, the fiufied fibrous pulp batt must have the properties of strength and integrity inasmuch as the batt is utilized as the core or center of the sanitary products and must therefore provide strength and integrity to the overall sanitary products. Also, it is desirable to have minimum fiber breakage from the mechanical fiberizing operation so that the ultime air-layed fluifed fibrous pulp batt will provide improved moisture absorption characteristics. Also, it is desirable for the wet pressed pulp sheet to be substantially completely fiberized to eliminate undesirable residual unfiberized sheet particles and minimize fiber dust so as to provide longer, stronger and more uniform fibers for producing greater loft and strength in the batt.

Accordingly, it is the object of this invention to provide a process for improving a fluifcd fibrous pulp batt adapted for use in sanitary products or the like wherein the fluflEed fibrous pulp batt has markedly improved strength and integrity with longer, stronger and more uniform fibers for producing greater loft, moisture ab sorption and strength in the batt.

It has been found by this invention that the above object may be accomplished by providing a process comprising the continuous steps of treating wet pulp fibers for effecting kinking and interlocking of the fibers, forming the fibers into a wet pressed pulp sheet, drying, mechanically fiberizing the sheet and air-laying the debonded kinked fibers to form a fluffed pulp batt with improved strength and integrity due to the kinked and interlocked fiber formation. Preferably, the process also includes the steps of producing a dilute, aqueous slurry of the kinked and interlocked fibers and incorporating in the slurry a cationic debonding agent, so that minimum breakage of the fibers will result during the mechanical fiberizing step due to the debonding effect of the cationic nature and a fiufl ed pulp batt will be produced with minimum fiber breakage therein.

By any conventional pulp making and paper making technique, the fibers produced are essentially non-kinked. That is, they exist as straight fibers in the wood and after going through cooking and bleaching process, are delivered to the paper making machine in essentially an unkinked form. Then, when they are formed into a sheet and dried, they are held in place by the structure of the sheet and essentially remain unkinked fibers in the dry sheet. Then, as in the case of fiberizing pulp, they are broken apart by mechanical means, the individual fibers obtained are still essentially unkinked. The air-laid batt formed of these fibers has relatively little strength and integrity. There is no bonding between dry fibers once separated and brought back into contact with one another and any type of stresses put on the batt, such as handling, or pulling, easily slides the fibers by one another resulting in breakage of the pad structure and the sanitary product utilizing the batt.

Referring now to the specific steps of the process of this invention, the present invention is applicable to practically all conventional types of pulps made in conventional manner by well-known kraft, soda, sulfite or neutral sulfite processes. The raw material, that is the fibers to be pulped, and otherwise processed in accordance with this invention, may be any one or more of the various types of cellulosic materials commercially used in paper and paperboard manufacture. Illustrative examples are wood, cotton, linters, flax, hemp, ramie, bagasse, esparto fiber pulps, etc. Generally speaking, it is desirable to use relatively long fiber material for ultimate individual fiber strength and for high resistance to breaking, powdering or dusting when subjected to fiberizing treatment.

Wet pulp fibers, of the above type, are treated for effecting kinking and interlocking of the fibers. This treating step for effecting kinking and interlocking of the fibers may be effected by the use of a mechanical kinking device, such as described in Hill et al. US. Pat. 2,516,384, issued July 25, 1950. The device of this patent is one example of a suitable device for treating wet pulp fibers for effecting kinking and interlocking of the fibers and any device that mechanically kinks wet fibers may be utilized within the context of this invention. In order to efiectin kink wet fibers, they should be dewatered to some extent and the kinking operation may include a separate dewatering step such as a screw press, or apparatus may be used that both dewaters and works the fibers into kinks with one operation. Such a combination action is produced in a Curlator" machine and is described in the section entitled The Curlator, pages 258-261, Pulp and Paper Manufacture, volume 2, 1st Edition, 2nd Impression published by McGraw-Hill Book Company, Inc. in 1951.

Next, a dilute, aqueous slurry of the kinked and interlocked fibers is produced, a cationic debonding agent is incorporated into the slurry and the slurry is formed into a wet pressed pulp sheet and dried.

Suitable cationic debonding agents .are disclosed in Hervey and George U.S. Pats. Re. 26,939, issued Aug. 18, 1970; 3,554,862, issued Jan. 12, 1971; and 3,554,863,

issued 1 an. 12, 1971, all of which are assigned to the as- In the specification there has been set forth a preferred signee of the present invention. These debonding agents embodimentofthe inyention and, a1though specific terms; may be generally classified as cationic long chain fatty] are mployed, they are used in a generic a nd.-descriptive alkyl compounds having at least twelve carbon atoms in' sense only-and not for purposes of limitation. at least one alkyl chain. 5 QWhat is claimed is: I

Depending upon the type of paper or board makingf LA process for forming a fluffed fibrous pulp batt'for. machinery'used, the desired speed of operation, and the, use in sanitary products, said process comprising the con desired degree of impregnation of the kinkedf fib'erswith tinuous steps ot mechanieally-treating. of web-pulp fibers the chemicals or debonding agent, the debon t fonetfecting kinking and interlocking of the fibers, produc incorporated into the wet slurry of kinked ing a ,dilute aqueous slurry of the kinked.and-interlockerstock chest or head box of the paper or paperboard nia fibers, incorporating -inthe slurry :a cationic debonding chine. A suitable type of Fourdrinier paper machine and agent,. forming the. wet slurry into a wet pressed-,- pulp the process of forming paper thereon is disclosed in Bed sheet,. drying the zsheet, mechanically fiberizing, said sheet,

well US. Pat. 2,488,700, issued Nov. 22, 1949; d a spit and,.air-l-ying the-, debonded kinked fibers to form fluffed able type of cylinder paper machine is disclosed i'n Edge 15 pulp hattyvith minimum fiber breakage and substantially U.S. Pat. 2,005,839, issued June 25, 193 e "repee'rnay improved strength andintegrity duesto the kinkedand inbe had to these patents for a disclosure. of e machines 'terlocked fiber formation. and processes of operation suitable for use thine present: 2. A process for forming a fluffed fibrous pulp batt for invention. use in sanitary products, said process comprising the con- The amount of debonding agent added toith e wet tinuous steps of mechanically treating of wet pulp fibers of fibers 'will 'vary within specific ranges the t'yp for efiecting kinking and interlocking of the fibers, forming pulp used. Reference may be had to the abovethree pate the kinked fibers into a wet pressed pulp sheet, drying the ents, assigned to the assignee of the presentfinve ntign, sheet, mechanically fiberizing the sheet, and air-laying the these specifics. v p fiberized kinkedlfib'ers to form a fluffed pulp batt with sub- 'After formation of a'dried, wet pressed pnlp sheet 25 stantially improved strength and integrity due to the kinked sheet is mechanically fiberized .into individual, .debpnded. and interlocked fiber formation. kinked fibers and air-laid to form a fluffed .p p batt. The I v mechanical fiberizing is performed with a/minimuln, of, fiber breakage due to the debonding etfect of 'h agent. The resulting flutfed pulp batthas m i References Cited I UNITED TATES PATENTS fiber breakage and substantially improved 1 eng 3,395,708 8/1968 Hervey et a1 -179 X A suitable machine for mechanically fibe 'zing and air- I 3,171,773 3/1965 Estes et a1 161 168 laying is disclosed in George US. Pat. 3, 5 43. ,3 5 1;, issued 2,516,384 7/1950 H111 ell 16-2100 Dec. 1, 1970, and assigned to the assigneejof th present. 3,556,931 mp e 11 in nti 135 3,370,590. '2/1968 Hokanson et a1. .1 62 .15 X,

Thus, it may be seen that the combination of reating $617,439 11/ Chapman 7 58 of wet pulp fibers for -elfecting kinking and int e cki ngof, 3,554,852 Hervey 81 162-458 the fibers and incorporating into a-slurry St lt: kinked, 1 H y 6t 2- and interlocked fibers acationic debonding age nt produces J I h a unique and novel wet pressed pulp sheet L'l y Pnmary e m r mechanically,vfiberizedfand air-laid with mi v ,l I a agofwqrzsfl duewtol tha debonding eficq 0t in A. L. CORBIN, Assistant Examiner agent and which forms a'flutfed pulp batt'with-s ly improved strength and i interlocked 1gb UNITED STATES A NT OFFICE: j CERTIFICATE OF CORRECTION Patent NU- 3,809,004 mg v May 7, 1574 lnven torgs) Phi llip waii'e- Estes V It is c ertified thz ltsrror apfissits al no iz's -i dgntif ied patent an d that said Letters Patent are hereby corre cted as shown belbw:

Column 1 line 17 after "inclu des dele t e -inbludes- I 7 Column 1 line '56 shang 'u1t iiins' fc ssfilitiinat'v? I I Cdlumfi 2; line i5 5 "'effes t ting fs" -'i 'f ve 1y 1 Column 4 li ne 8 ,1; change" Y'Qeb" t o -'\:v e1 I I r Column line 10, change "ihtefl''bk r'ifto, in 1 :er1 o :kd'

Signed ail-(1' seale d this 10th day p ise ie'mber 1974.

(SEAL) Attest:

MCCOY M. GIBSON, JR; s MA SHALL fDANN Attesting Officer I :QOmfiiis' s-ione'r 0fil ten t s 

